Drill bit



April 28, 1931.

c. H. M. BULL DRILL BIT Filed Aug. 16, 1927 I 2 Sheets-Sheet 1 April 28, 1931- c. H.IM. BULL 1,802,872

Patented Apr. 28, 1931 v UNITED STATES PATENT OFFICE I onnrron n. M. BULL, or HOUSTON, TEXAS, ASSIGNOR T m1) Roman m GOMPANY,

on nous'ron, Texas, A CORPORATION on TEXAS I DRILL BIT Application filed August 16, 1927. Serial No. 213,249.

This invention relates to deep well drillin apparatus, and more particularly to drill bits.

The invention has for its object the pro-- Fig. 3 is a section on-the hne 3-3 of Fi 1.

Fig. 4 is a bottom plan view, the cutter sections being in their outer position.

Referring specifically to the drawings, the bit head comprises an upper or main section 1 and lower or cutter sections 2, 2; the latter having inwardly and downwardly inclined spindles 8 with bushings 9 thereon, upon which cutters 10, 10 are rotatably mounted. Each of the cutter sections 2, 2 is provided with a circular recess 2a in its upper end to receive annular flange 1a of main section 1. A pin 3 is screwed into cutter section 2 and extends upwardly into section 1, as

shown. Any suitable means such as locking pin 4:, may be employed to lock pin 3 in main sectionl, said section being bored for the reception thereof.

Main section 1 has oppositely disposed depending extensions 16, 16 said extensions having concaved outer surfaces 16' to receive the rounded cutter sections 2, and having grooves 16 in the inner surfaces thereof to receive flanges 2b of cutter sections 2, when the said cutter sections are swung inwardly into operative position.

The assembly of the above elements is effected as follows: Cutters 10 having been mounted on the cutter sections, pins 3 are first screwed a predetermined distance into said cutter sections. The main section 1 having been placed upside down on the derrick floor or other suitable support, the cutter sections are then placed immediately above and adjacent to the main section in the outer position illustrated by Fig. 4, so that pins 3 enter the main section, and annular flanges 1a of the main section enter circular recesses 2a of the cutter sections. Lockin pins 4 are then driven in to nonrotatab y lock pin 3 in the main section.

In this position, the cutter sections are not abutting against the main section, but are spaced therefrom a predetermined dis tance, for a purpose which will now ap ear.

When the cutter sections are swung rom the outer or inoperative position illustrated in Fig. 4, to the inner or operative position illustrated in Fig. 1, the said cutter sections are moved into tight contact with the main section to be firmly supported thereby. The tight fit between said sections also prevents the entry therebetween of dirt and other foreign matter. The movement of the cutter sections toward the main section, which attends such rotary movement of the former with respect to the latter, is effected by the threads of the cutter sections and the threads of the pin 3 which are engaged, the said pin having theretofore been locked against rotation. Bolts 5 are then inserted in the bores provided for the same in the main section, and the nuts 6 applied to said bolts to lock the cutter sections in their inner or operative position, the overlapping heads 5a of said bolts preventing outward movement of said cutter sections. It will be observed that the main section and cutter sections have grooves 10 and 20, respectively, to receive the heads 5a, to'permit the same to be substantially flush with the sides of the bit, and to prevent rotation thereof.

Those skilled in the art will immediately perceive that the great stress and strains to which a bit is subjected in deep well drilling will easily be withstood by the interfitting elements which constitute the assembled bit. The pins 3 and annular flanges l a projecting downwardly into the cutter sections, the flanges 2b projecting laterally into the grooves 16 of main section extensions 1b, the rounded surfaces of the cutter sections snugly fitting the concave surfaces 16' of extensions 16, and finally the bolts 5all serve to render the connection between the main section and the cutter sections so strong that when the latter are mounted on the former, the assembled head has a strength very nearly equal to the strength it would have were the sections made integral.

The use of the device is characterized by case and simplicity. The substitution of new cutters for old is a task which drillers are frequently and continually called upon to perform. The advantageous use of the present device can perhaps best be illustrated by specifically comparing the same with one of the many types of roller bits now in use. The drawings illustrate a general type of roller bit employing a pair of substantially conical roller cutters 10, 10, mounted on spindles 8 that incline downwardly and inwardly toward the longitudinal axis of the head, so that there is very little clearance between the cutters.

Those skilled in the art know that the heads of such bits have heretofore been made in two pieces, in order that the cutters could be mounted upon and removed from the spindles; and that in the use of the two-piece head various obstacles have arisen, of which there need be mentioned only the difliculty experienced by the driller in separating the pieces of the head, supporting one piece at a time and exchanging cutters, and putting the two pieces together again in a clean condition.

The present invention eliminates these obstacles, and so is particularly useful where roller cutters are used because the sections when assembled need never be taken apart, and the bit may be placed upside down on the derrick floor so that the meeting surfaces of the sections will not be in contact with mud and the cutters will be supported in a position where they can be easily handied. In exchanging cutters after the bit has been so positioned, itis necessary only to loosen the nuts 6 on bolts 5, pull said bolts outwardly just far enough to enable the heads 5a to clear the sides of grooves 10 and 2c, rotate said bolts so that the heads 5a will not overlap the cutter sections, and swing the cutter sections outwardly about one-quarter of a revolution. It will be noted that none of the parts have been taken a art. The old cutters may then be removed From the spindles and new cutters substituted, after which it is necessary only to swing the cutters back into operative position, holding the heads 5a out of the path thereof, release the heads, and tighten the nuts. Heads 5a, acted on by the force of gravity will normally assume the position shown in Fi 1.

ardinarily, there will be no need to sepaposed members, the outer sur rate the main and cutter sections. Should separation thereof for any reason be desired, however, it is necessary only to swing the cutter sections about one-quarter of a revolution outwardly and knock out the locking pin 4. The cutter sections may then be removed. The cutter sections cannot be screwed off the pin 3 while the latter is locked in the main section, because extensions 1-?) lie in the path of said cutter sections and will arrest the continued rotation thereof.

Many advantages and uses, other than those above referred to, will be apparent to those skilled in the art.

While the invention is particularly useful where roller cutters are employed and such use has been illustrated and described, it is to be understood that it is not limited either to use in connection with a particular type of roller cutter or to roller cutters generally.

Various changes in the preferred embodiment shown may be made within the scope of the following claims.

I claim:

1. A drill having a cutter recess, a main section, a cutter section mounted for rotation on said main section about a vertical axis, means to lock said cutter section against rotation, a cutter on said cutter section, said main section having a depending grooved extension and said cutter section having a flange to fit into the groove of said extension to prevent rocking of said rotatable cutter section about a horizontal axis.

2. A drill bit having a main section, a pair of cutter sections rotatably mounted on said main section and having laterally projecting flanges, said main section having an extension comprising a pair of opfpositely disaces of said members being concave and the inner surfaces of said members being grooved, to receive said cutter sections and the flanges thereof, cutters mounted on said cutter sections and means to lock said cutter sections against rotation.

3. A drill bit head having a main section and a pair of cutter sections, one of said cutter sections being so mounted on said main section that it is rotatable on an axis substantially parallel with the longitudinal axis of the head, means to lock said rotatable cutter section against rotation, and cutielS rotatably mounted on said cutter sections.

4. A drill bit head comprising a main section and a pair of cutter sections rotatably mounted on said main section, the axes of rotation of said cutter sections being substantially parallel with the longitudinal axis of the head, means to lock said cutter sections against rotation, said cutter sections having inclined faces, and cutters rotatably mounted on said inclined faces.

tions orming a recess in the bottom of the head, splndles on sald cutter sections pro- 'jecting into said recess, cutters on said spindles, one of said cutter sections being so mounted on said main section that it is rotatable on an axis substantially parallel with the longitudinal axis of the head, and means to lock said rotatable cutter section against rotation.

6. A roller bit head having a main section and a pair of cutter sections, said cutter sections having threaded sockets, a pair of pins remova-bly locked in said main section and having screw threaded ends fitting in said sockets, means to lock said cutter sections against rotation, inwardly and downwardly projecting spindles on said cutter sections, and substantially frusto-conical roller cutters on said spindles.

7. A drill bit head having a cutter recess in the bottom thei'eof, a main section and a cutter section, said cutter section forming one wall of saidrecess, a screw-threaded pin vertically mounted. inf's'aid main section and projecting downwardly therefrom, said cutter section having a screw-threaded socket in its upper end to receive said pin, a cutter on said cutter section, and means to lock said cutter section against rotation on said pin. v

8. In a roller bit, a head having a main section and a pair of cutter sections mounted on said main section for rotation about axes substantially parallel with the longitudinal axis of said head and forming a cutter recess at the bottom of the head, said head having a centrally disposed depending extension having grooved and rounded portions on each side, each of said cutter sections having rounded and flanged portions to engage one side of said extension, and means to lock said cutter sections against rotation.

9. In a roller bit, a head having a.main section and a pair of cutter sections mounted on said main section for rotation about axes substantially parallel with the longitudinal axis of said head, and having beveled lower ends to form a substantiall V-shaped recess in the bottom of said hea cutter spindles on said ends and adapted to project into said recess, cutters on said spindles, supporting means depending centrally from said main section, and means to hold said cutter sections in engagement with said supporting means.

10. In a roller bit, a head having a main section, a pair of threaded pins supported by said main section so that their axes are substantially parallel with the longitudinal axis of the head, said pins projecting outwardly from said main section, a pair of cutter sections, each of said cutter sections having a screw-threaded socket into which one .of said pins extends to rotatably su port said cutter section, said cutter sections orming a recess in the bottom of the head, outters on said cutter sections adapted to,

occupy said recess, and means to lock said cutter sections against rotation on said pins. In testimony whereoflI hereunto aflix my signature.

CLINTON H. M. BULL. 

